Thermal (Kapitza) resistance of interfaces in compositional dependent $ZnO-In_2O_3$ superlattices

Abstract

Compositionally dependent superlattices, $In_2O_3$ $(ZnO) _k$, form in the $ZnO$-rich portion of the $ZnO-In_2O_3$ phase diagram, decreasing thermal conductivity and altering both the electron conductivity and Seebeck coefficient over a wide range of composition and temperature. With increasing indium concentration, isolated point defects first form in $ZnO$ and then superlattice structures with decreasing interface spacing evolve. By fitting the temperature and indium concentration dependence of the thermal conductivity to the Klemens-Callaway model, incorporating interface scattering and accounting for conductivity anisotropy, the Kapitza resistance due to the superlattice interfaces is found to be $5.0 ± 0.6 × 10^{−10} m^2K/W$. This finding suggests that selecting oxides with a compositionally dependent superlattice structure can be a viable approach, unaffected by grain growth, to maintaining low thermal conductivity at high temperatures.Engineering and Applied Science